Question

The radioactivity of certain radioactive element drops to ${\left(\frac{1}{8}\right)}^{th}$ of its initial value in 30 second, its half life is:

• A. 15 second
• B. 5 second
• C. 4 second
• D. 10 second

Answer 1

The correct option is D 10 second

$3.t_{\frac{1}{2}}=30$

$\Rightarrow t_{\frac{1}{2}}=10$

Hence,

option $D$ is correct answer.